git.m6w6.name Git - m6w6/seekat/blob - lib/API/Invoker.php

   1 <?php
   2
   3 namespace seekat\API;
   4
   5 use Generator;
   6 use http\Client;
   7 use React\Promise\{
   8         Deferred,
   9         ExtendedPromiseInterface,
  10         PromiseInterface,
  11         function all
  12 };
  13
  14 class Invoker extends Deferred
  15 {
  16         /**
  17          * The HTTP client
  18          * @var Client
  19          */
  20         private $client;
  21
  22         /**
  23          * The return value of the generator
  24          * @var mixed
  25          */
  26         private $result;
  27
  28         /**
  29          * Cancellation flag
  30          * @var bool
  31          */
  32         private $cancelled = false;
  33
  34         /**
  35          * Create a new generator invoker
  36          * @param Client $client
  37          */
  38         function __construct(Client $client) {
  39                 $this->client = $client;
  40
  41                 parent::__construct(function($resolve, $reject) {
  42                         return $this->cancel($resolve, $reject);
  43                 });
  44         }
  45
  46         /**
  47          * Invoke $generator to create a \Generator which yields promises
  48          *
  49          * @param callable $generator as function():\Generator, creating a generator yielding promises
  50          * @return Invoker
  51          */
  52         function invoke(callable $generator) : Invoker {
  53                 $this->iterate($generator());
  54                 return $this;
  55         }
  56
  57         /**
  58          * Iterate over $gen, a \Generator yielding promises
  59          *
  60          * @param Generator $gen
  61          * @return Invoker
  62          */
  63         function iterate(Generator $gen) : Invoker {
  64                 $this->cancelled = false;
  65
  66                 foreach ($gen as $promise) {
  67                         if ($this->cancelled) {
  68                                 break;
  69                         }
  70                         $this->give($promise, $gen);
  71                 }
  72
  73                 if (!$this->cancelled) {
  74                         $this->resolve($this->result = $gen->getReturn());
  75                 }
  76                 return $this;
  77         }
  78
  79         /**
  80          * Get the generator's result
  81          *
  82          * @return ExtendedPromiseInterface
  83          */
  84         function result() : ExtendedPromiseInterface {
  85                 return $this->promise();
  86         }
  87
  88         /**
  89          * Promise handler
  90          *
  91          * @param array|PromiseInterface $promise
  92          * @param Generator $gen
  93          */
  94         private function give($promise, Generator $gen) {
  95                 if ($promise instanceof PromiseInterface) {
  96                         $promise->then(function($result) use($gen) {
  97                                 if (($promise = $gen->send($result))) {
  98                                         $this->give($promise, $gen);
  99                                 }
 100                         });
 101                 } else {
 102                         all($promise)->then(function($results) use($gen) {
 103                                 if (($promise = $gen->send($results))) {
 104                                         $this->give($promise, $gen);
 105                                 }
 106                         });
 107                 }
 108                 $this->client->send();
 109         }
 110
 111         /**
 112          * Cancellation callback
 113          *
 114          * @param callable $resolve
 115          * @param callable $reject
 116          */
 117         private function cancel(callable $resolve, callable $reject) {
 118                 $this->cancelled = true;
 119
 120                 /* did we finish in the meantime? */
 121                 if ($this->result) {
 122                         $resolve($this->result);
 123                 } else {
 124                         $reject("Cancelled");
 125                 }
 126         }
 127 }